Department of Surgery, The University of Kentucky, Lexington, Kentucky, United States of America.
PLoS One. 2011;6(5):e19882. doi: 10.1371/journal.pone.0019882. Epub 2011 May 16.
TNF-related apoptosis-inducing ligand (TRAIL; Apo2) has been shown to promote intestinal cell differentiation. Nuclear factor of activated T cells (NFAT) participates in the regulation of a variety of cellular processes, including differentiation. Here, we examined the role of NFAT in the regulation of TRAIL in human intestinal cells. Treatment with a combination of phorbol 12-myristate 13-acetate (PMA) plus the calcium ionophore A23187 (Io) increased NFAT activation and TRAIL expression; pretreatment with the calcineurin inhibitor cyclosporine A (CsA), an antagonist of NFAT signaling, diminished NFAT activation and TRAIL induction. In addition, knockdown of NFATc1, NFATc2, NFATc3, and NFATc4 blocked PMA/Io increased TRAIL protein expression. Expression of NFATc1 activated TRAIL promoter activity and increased TRAIL mRNA and protein expression. Deletion of NFAT binding sites from the TRAIL promoter did not significantly abrogate NFATc1-increased TRAIL promoter activity, suggesting an indirect regulation of TRAIL expression by NFAT activation. Knockdown of NFATc1 increased Sp1 transcription factor binding to the TRAIL promoter and, importantly, inhibition of Sp1, by chemical inhibition or RNA interference, increased TRAIL expression. These studies identify a novel mechanism for TRAIL regulation by which activation of NFATc1 increases TRAIL expression through negative regulation of Sp1 binding to the TRAIL promoter.
肿瘤坏死因子相关凋亡诱导配体（TRAIL；Apo2）已被证明可促进肠细胞分化。活化 T 细胞核因子（NFAT）参与多种细胞过程的调节，包括分化。在这里，我们研究了 NFAT 在 TRAIL 调节中的作用在人类肠细胞中。用佛波醇 12-肉豆蔻酸 13-醋酸盐（PMA）和钙离子载体 A23187（Io）的组合处理增加了 NFAT 激活和 TRAIL 表达；用钙调神经磷酸酶抑制剂环孢素 A（CsA）预处理，一种 NFAT 信号的拮抗剂，减少了 NFAT 激活和 TRAIL 诱导。此外，NFATc1、NFATc2、NFATc3 和 NFATc4 的敲低阻断了 PMA/Io 增加的 TRAIL 蛋白表达。NFATc1 的表达激活了 TRAIL 启动子活性，并增加了 TRAIL mRNA 和蛋白表达。从 TRAIL 启动子中删除 NFAT 结合位点并没有显著削弱 NFATc1 增加的 TRAIL 启动子活性，这表明 NFAT 激活对 TRAIL 表达的间接调节。NFATc1 的敲低增加了 Sp1 转录因子与 TRAIL 启动子的结合，重要的是，Sp1 的化学抑制或 RNA 干扰抑制增加了 TRAIL 表达。这些研究确定了 TRAIL 调节的一种新机制，其中 NFATc1 的激活通过负调控 Sp1 与 TRAIL 启动子的结合来增加 TRAIL 表达。
